Evaluation of the Physical, Mechanical, and Calorific Properties of Briquettes with or without a Hollow Made of Wheat (Triticum aestivum L.) Straw Waste

Abstract

Large amounts lignocellulosic biomass in the form of straw is leftover after wheat harvesting that could be utilized for beneficial purposes. The latter has led to the emergence of new technologies to make use of this resource. One such technology currently in use turns wheat straw into briquettes. In the present study, we have prepared and evaluated the physical, mechanical and calorific properties of two types of briquettes made of wheat straw. The two types of briquettes prepared were (i) hollow briquettes and (ii) solid briquettes. The densities of these briquettes obtained on a mechanical device with a crank mechanism were 1.169 kg/m3, irrespective of whether the briquettes were hollow or solid. The briquette densities are consistent with European standards. The calorific value of wheat straw was 17.69 MJ/kg. Although the calorific value was somewhat lower than the beech wood briquettes (18.38 MJ/kg), it is adequate for their combustion in both stoves and thermal power plants. The ash content of wheat straw was 9.1% (~10-fold higher than that of beech wood). The briquettes showed a compressive mechanical strength of 1.15–2.17 N/mm2 and splitting mechanical strength of 0.17–0.39 N/mm2 suggesting that the straw briquettes were well compacted and can be stable during transport and/or other manipulations. In conclusion, wheat straw briquettes have similar physical, mechanical and calorific properties to those prepared from beech wood biomass and are a viable solution to replace beech wood briquettes with similar efficiency.